Among numerous Explosive-Detection Systems, the CT technology has become prevailing in the aviation security field due to its low false alarm rate and low failed reporting rate. However, the Explosive-Detection System using the CT technology is bulky and costly, which limits the further application.
Though an improved CT Explosive-Detection System having a small volume and a lower cost has been developed recently, the speed at which the object to be inspected passes therethrough is reduced a lot compared to the conventional CT Explosive-Detection System, which also bottlenecks the promoting of it.
In addition, an Explosive-Detection System including a DR imaging apparatus and a CT imaging apparatus is available in the market. The DR imaging apparatus usually obtains data of an object to be inspected in a time triggered mode, specifically, the DR imaging apparatus emits beams at a regular time interval, and detectors receive the beams penetrating the object and convert received information into digital information. This kind of time triggered mode requires a uniform speed of the DR imaging apparatus relative to the object.
However, the adding of the DR imaging apparatus increases the length of the Explosive-Detection System; in addition, the inspecting speed of the CT imaging apparatus is lower than that of the DR imaging apparatus, therefore, the speed at which the object passes the Explosive-Detection System is decreased. In order to obtain the Explosive-Detection System having a small overall dimension, the length added by the DR imaging apparatus has to be as small as possible, thus, the distance between the CT imaging apparatus and the DR imaging apparatus is designed to be small enough.
Further, if the whole length of the object is longer than a distance between a beam plane of the CT imaging apparatus and a beam plane of the DR imaging apparatus, there is the case that the object is scanned by the DR imaging apparatus and the CT imaging apparatus at the same time. In view of the above, the speed at which the object passes the DR imaging apparatus is the same as the speed at which the object passes the CT imaging apparatus in the prior art.
However, the problem is that the imaging time of the DR imaging apparatus is much less than that of the CT imaging apparatus, which means the whole Explosive Detection System has to be operated at a lower speed suitable for the CT imaging apparatus. Thus, if the Explosive Detection System operates at a high speed when the object is scanned by the DR imaging apparatus and operates at a low speed when the object is scanned by the CT imaging apparatus, the average speed at which the objects passes the Explosive Detection System will be increased. In that case, however, the same object is scanned by the DR imaging apparatus at different speeds, which results in distortion of the formed image (as shown in FIG. 2) if no measures are taken, and thus the technical performance of the Explosive Detection System will be deteriorated.